#SwimmyFallon, as he came to be known on Twitter, agreed to take part in the plunge to benefit the Special Olympics after a nearly week-long exchange with Emanuel.

It all started when Fallon openly expressed his desire to have Emanuel on the show. The mayor agreed to do it if Fallon took part in the Polar Plunge. The twitterverse got involved, egging Fallon on with the hashtag #JimmyPlungeWithUs, and the comedian on Wednesday finally confirmed he'd take part.

"I'm a man of my words. I'm a man of my tweets," said Fallon.

NBC Chicago is a media sponsor for Sunday's event at North Avenue Beach. Forecast models predict temperatures in the 20s with steady snow that could become heavy that morning.